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Plastic production reached 400 million tons in 2022 (ref. 1), with packaging and single-use plastics accounting for a substantial amount of this2. The resulting waste ends up in landfills, incineration or the environment, contributing to environmental pollution3. Shifting to biodegradable and compostable plastics is increasingly being considered as an efficient waste-management alternative4. Although polylactide (PLA) is the most widely used biosourced polymer5, its biodegradation rate under home-compost and soil conditions remains low6–8. Here we present a PLA-based plastic in which an optimized enzyme is embedded to ensure rapid biodegradation and compostability at room temperature, using a scalable industrial process. First, an 80-fold activity enhancement was achieved through structure-based rational engineering of a new hyperthermostable PLA hydrolase. Second, the enzyme was uniformly dispersed within the PLA matrix by means of a masterbatch-based melt extrusion process. The liquid enzyme formulation was incorporated in polycaprolactone, a low-melting-temperature polymer, through melt extrusion at 70 °C, forming an ‘enzymated’ polycaprolactone masterbatch. Masterbatch pellets were integrated into PLA by melt extrusion at 160 °C, producing an enzymated PLA film (0.02% w/w enzyme) that fully disintegrated under home-compost conditions within 20–24 weeks, meeting home-composting standards. The mechanical and degradation properties of the enzymated film were compatible with industrial packaging applications, and they remained intact during long-term storage. This innovative material not only opens new avenues for composters and biomethane production but also provides a feasible industrial solution for PLA degradation.

Present estimates suggest that of the 359 million tons of plastics produced annually worldwide1, 150–200 million tons accumulate in landfill or in the natural environment2. Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic, with almost 70 million tons manufactured annually worldwide for use in textiles and packaging3. The main recycling process for PET, via thermomechanical means, results in a loss of mechanical properties4. Consequently, de novo synthesis is preferred and PET waste continues to accumulate. With a high ratio of aromatic terephthalate units—which reduce chain mobility—PET is a polyester that is extremely difficult to hydrolyse5. Several PET hydrolase enzymes have been reported, but show limited productivity6,7. Here we describe an improved PET hydrolase that ultimately achieves, over 10 hours, a minimum of 90 per cent PET depolymerization into monomers, with a productivity of 16.7 grams of terephthalate per litre per hour (200 grams per kilogram of PET suspension, with an enzyme concentration of 3 milligrams per gram of PET). This highly efficient, optimized enzyme outperforms all PET hydrolases reported so far, including an enzyme8,9from the bacterium Ideonella sakaiensisstrain 201-F6 (even assisted by a secondary enzyme10) and related improved variants11–14that have attracted recent interest. We also show that biologically recycled PET exhibiting the same properties as petrochemical PET can be produced from enzymatically depolymerized PET waste, before being processed into bottles, thereby contributing towards the concept of a circular PET economy.

A new small-scale fire test is described in this paper. The goal was to design a high-throughput test permitting the optimization of intumescent mastic coatings formulated to protect steel in the case of hydrocarbon fire. This type of coating, applied on steel plates, beams, or columns, is usually evaluated in large industrial furnaces. Such experiments are expensive and time-consuming. The development of a small-scale laboratory test using an external heat flux is investigated. Temperature as a function of time is recorded on the back of the coated steel panel. It is shown that temperature profiles are very well correlated with those measured in industrial furnaces. This low-cost and fast test is very repeatable, and it allows rapid screening of a large number of different coating formulations. The test also shows good correlation with the results obtained in cellulosic fire testing.

The goal of this work is to combine small-scale screening tests permitting, during the laboratory research phase of a development, the optimization of intumescent mastic coatings formulated to protect steel in the case of hydrocarbon fire. This type of coating, applied on steel plates, beams, or columns, is usually evaluated in large industrial furnaces. Such experiments are, however, expensive and time-consuming. The use of such tests, if they are essential since they give a good simulation of a real fire, is a break for the development of new intumescent high-performance intumescent coatings. The original combination of small-scale laboratory tests, such as thermogravimetric analyses and rheological measurements, provides, through a rapid screening of a large number of formulations, a very interesting preliminary tool for the development of new intumescent coatings. A statistical approach involving principal component analysis has been successfully used to correlate the results of the industrial furnace tests with those from the laboratory-scale analyses.

Among all of the methods used for the development and study of the degradation of a polymer, thermogravimetric analysis (TGA) is the most widespread. This study is interested in the modelling of the mass losses of rigid polyurethane foam under linear heating rates in an inert atmosphere using the Invariant Kinetic Parameters (IKP) method. The degradation of rigid polyurethane foam is a five‐stage process under a nitrogen atmosphere. The first stage of degradation has not been modelled because of too low a number of points. The model of potential law for the second stage, the model of reaction order for the third stage and a mixture of reaction order, phase‐boundary reaction and nucleation for the fourth stage are found to be the most adequate ones. Copyright © 2003 John Wiley & Sons, Ltd.

Among all of the methods used for the development and study of the degradation of a polymer, thermogravimetric analysis (TGA) is the most widespread. This study is interested in the modelling of the mass losses of rigid polyurethane foam under linear heating rates in an inert atmosphere using the Invariant Kinetic Parameters (IKP) method. The degradation of rigid polyurethane foam is a five-stage process under a nitrogen atmosphere. The first stage of degradation has not been modelled because of too low a number of points. The model of potential law for the second stage, the model of reaction order for the third stage and a mixture of reaction order, phase-boundary reaction and nucleation for the fourth stage are found to be the most adequate ones. Copyright © 2003 John Wiley & Sons, Ltd.

In [Zagier and Kramarz 87], the authors computed the critical value of the L-series of the family of elliptic curves x3+ y3= mand they pointed out some numerical phenomena concerning the frequency of curves with a positive rank and the frequency of occurrences of the Tate-Shafarevich groups III in the rank 0 case (assuming the Birch and Swinnerton-Dyer conjecture). In this paper, we give a similar study for the family of elliptic curves associated to simplest cubic fields. Thesecurves have a nonzero rank and we discuss the density of curves of rank 3 that occurs. We also remark on a possible positive density of nontrivial TateShafarevitch groups in the rank 1 case. Finally, we give examples of curves of rank 3 and 5 for which the group III is nontrivial.

Abstract:  By using the so-called elliptic curve Chabauty method, N. Bruin [1], V. Flynn and J. Wetherell [6] have extended Chabauty's method to some cases where the rank of the Jacobian may not be less than the genus. The main tool in these methods is a theorem of Strassman on p-adic zeros of power series in one variable, and is applicable only if certain Jacobians are of rank less than or equal to 1. In the present paper, we give an explicit generalization of Strassman's theorem to several variables, enabling us to treat cases where the rank is greater than 1. We apply this to find all the rational points on a hyperelliptic curve of rank and genus equal to 4.

This study investigates the thermal stability of poly(p‐phenylenediamine‐terephtalamide) (PPT) and poly(p‐phenylenebenzobisoxazole) (PBO) fibres. Excellent behaviour of PBO is shown in comparison to that of PPT. The thermal stability (under pyrolytic or thermo‐oxidative conditions) of PBO is 150 °C higher than that of PPT. Moreover, the strong influence of oxygen, which plays the role of an initiator of degradation, on the degradation of fibres is shown. Using the invariant kinetic parameter (IKP) method, it is shown that the degradation rate of PBO is strongly reduced in comparison with that of PPT. It provides a simulation of the ‘fuel flow’ able to feed the flames, which can explain the high fire performance of PBO compared to PPT.© 2001 Society of Chemical Industry

An ELISA has been developed for the quantification of metallothioneins (MT) in liver from different species of fish. MT has also been quantified by RIA and DPP to allow a comparison between the methods. The immunoassays were carried out with a polyclonal antibody raised against perch (Perca fluviatilis) hepatic MT [1] which cross-reacted with hepatic MT from dab (Limanda limanda), lemon-dab (Microstomus kitt), and cod (Gadus morhua). The ELISA was more sensitive for the detection of MT from the flatfish than RIA and DPP. The detection limits of MT by immunoassays were lower for fish caught in the field than for Cd-injected fish. The immunoreactivity differed between MT from different fish species, more markedly between fish MT and rabbit MT. MT values determined by the three methods have been compared and showed that the results were similar and significantly correlated. Advantages and disadvantages of the ELISA are discussed in relation to the other methods.

The article discusses the development of an environment-friendly textile fire proofing process. It explores flame retardant solutions for textiles, use of renewable resources for creating fireproof nonwoven materials, and possible application of recycled polymeric materials for fire retardant polyester fibers. Some textile materials with high thermal resistance are cited including phenolic resins and polyimides. The flame retardant properties of composites based on flax fiber are also noted.